VP Foundation
- Lesson3 of 6
- Time70 min
Camera, lens and tracking
Outcome
Explain how tracking, lens data and genlock make the wall follow the camera, and how to avoid moiré.
Mapped to 3 ScreenSkills checklist lines
- ScreenSkills virtual production competencies: camera roles · Setting up camera and related equipment for virtual production: "in conjunction with tracking suppliers consider best tracking crown for style of shooting"
- ScreenSkills virtual production competencies: camera roles · Setting up camera and related equipment for virtual production: "carry out sync and gen lock tests, calibrate tracking and ensure 3D tracking is functioning"
- ScreenSkills virtual production competencies: VFX creation (virtual art department) roles · Create and match live action camera movements in 3D, including use of real-time tracking solutions: "calibrate each lens to identify and remove distortion"
ScreenSkills checklists are guides, not accreditation. This course is not endorsed by ScreenSkills.
Watch
4 films · about 88 minutes
Your browser blocked the player's tracking script, so watch time can't be credited here. Use the demo skip below.
More like this: Virtual production path
Films are made and owned by the channels named, and play from YouTube. Inclusion here is not an endorsement either way.
Tracking
- Tracking tells the engine where the camera is and where it points, many times a second. Optical systems read markers on the ceiling or the set; others use sensors on the camera.
- The tracking 'crown' or sensor sits on the camera. Its position must be measured and kept fixed, or the wall drifts.
- Calibrate at the start of every day and whenever the camera build changes.
Lens data
- The engine must know focal length, focus distance and distortion, or the wall's perspective won't match the lens.
- Encoders on the lens send focus and zoom. Each lens is calibrated for distortion before the shoot.
- Depth of field: the camera sees the wall as a flat screen at one distance. The engine softens the world to fake the right depth.
Timing and moiré
- Genlock locks camera, wall and engine to one timing signal. Without it the image can tear or flicker.
- Moiré appears when focus lands on or near the wall's pixels. Keep focus on the actors and enough distance between them and the wall.
- Some filters behave differently in front of LED. Test before the day.
Check
3 questions drawn from 8 · pass mark 80% · safety-critical questions must be right · 3 attempts in 24 hours · new questions each time
Watch the films to open the check.
Do
Moiré from a frame grab · 20 minutes
Read the description of a frame grab. Explain what's wrong, why, and three ways to fix it, in the order you'd try them.
Medium close-up, 85mm at T2. The actor stands 1.5m from the wall. Focus is set on the actor's ear, but the focus puller has racked to the wall for a moment to read a sign in the world. Fine ripples appear across the sign and the sky.
How it's marked
- Names moiré
- Explains it: focus landed on or near the LED pixels
- Fixes: keep focus off the wall; more distance between actor and wall; change lens or stop; ask the brain bar to move the sign into the world (soften it)
- Fixes in a sensible order
Met or Not yet, with a comment from a trained reviewer. Until accounts open, open the model answer after you submit and mark your own work against it.
Model answer (open after you submit)
Moiré: the rack put focus on the wall's pixels, and at 1.5m the wall is close enough to show the pixel grid. Fixes: 1 don't rack to the wall; 2 move the actor further from the wall; 3 stop down less or change lens to soften the wall; 4 ask the brain bar to place or blur the sign so it reads without focus on the wall.
Reflect
Record
This is everything kept about this lesson. In the pilot it's held by Futures in Film CIC in your account; Screen Sisters CIC sees named records only if you agree. Your data
Moving on doesn't complete a lesson. A lesson is complete when the films are watched, the check is passed and the task is marked Met.